A New Technology Of Detecting SSR And The Construction Of A Genetic Linkage Map For An Interspecific Hybrid Population Between Populas Adenopoda×P.alba Using SSR Markers

As a model system of plant biology and genetic , construction genetic linkage of Poplar plays an important role theory research in plant and has applied future. Using microsatellite markers to construct genetic linkage map for an interspecific F1 hybrid population between Populus adenopoda×P. alba will provide a platform for comparisons with linkage maps of Poplar and identification of traits useful in management and breeding using molecular marker.We report a molecular genetic linkage map for an interspecific hybrid population between Populas adenopoda×P. alba following the two-way pseudo-testcross mapping strategy. In the study We randomly selected 190 offspring from about 1400 offspring of an interspecific F1 hybrid cross. 639 pairs of SSR fluorescent dye-labelled primers derived from P. trichocarpa genome which include 286 pair of SSR markers of common fluorescent dye-labeled and 353 pairs of SSR markers using the TP-M13 automated fluorescent-labeled system were screened. Among 639 pairs of SSR markers, 426 pairs amplified, 100 pairs showed polymorphisms, and the frequent of amplification was 66.67%. Because of high hybridization of genetic background of Poplar which is outcross species , the segergation patterns of linkage of markers in a full-sib family of a specific hybrid cross is also different. We had detect 16 segregation patterns , which were not found in self-cross species.The linkage map between Populas adenopoda×P. alba has 71 markers . Twenty one linkage groups were constructed. Two groups has 6 SSR markers, one group has 5 SSR markers, seven groups has 4 SSR markers, four triplet and seven doublet. But 39 markers had not been linked and the average number of loci is 3.38.Map length is between 11.0cM~101.3cM, which 59.13 cM was average group length. The average interval was 24.8 cM between adjacent markers , the largest is 54.5 cM and the smallest is 1.2 cM. A total of 1241.7cM was observed. The genome length was estimated to be 2303.45cM, and genome coverage was estimated to be 59.46% at 20cM per marker. Departure from Mendelian expectations for the segregation of individual markers was assessed using X2–tests. 25 SSR primes were segregation distort markers, and 6 markers were not been linked.25 homological SSR markers were primarily used to comparative mapping between our map and P. trichocarpa×P. deltoides map. Only 5 homological linkage groups were aligned. But the number of homological SSR markers per group is only 2, so the orthologous markers can not show the synteny between the two maps.